A super absorbent polymer (SAP) is a synthetic polymeric material capable of absorbing moisture in about 500 to 1000 times its own weight. Various manufacturers have been denominated it as different names such as SAM (Super Absorbency Material), AGM (Absorbent Gel Material) or the like. Since super absorbent polymers started to be practically applied in sanitary products, they have been widely used for hygiene products such as disposable diapers for baby, water releasing agent for gardening, moisture resistant materials for the civil engineering and construction, cooling agents for blood or food during transportation.
The known preparation process for such super absorbent polymers includes a process by reverse phase suspension polymerization and a process by solution polymerization. The process by solution polymerization further includes a thermal polymerization method in which a water-containing gel polymer is polymerized while being broken and cooled in a kneader equipped with a plurality of shafts, and a photo-polymerization method in which an aqueous solution with a high concentration is irradiated with UV rays or the like onto a belt to be polymerized and dried at the same time.
Meanwhile, surface-treatment of the polymer powder obtained during polymerization, pulverization, drying and final pulverization processes has been attempted to obtain a water-containing gel polymer having more excellent physical properties, or modifications in various processes have been attempted to increase the efficiency of the polymerization, pulverization and drying steps.